ESP Chip Startup Time Optimization

[English]

Introduction

The startup time of ESP chips refers to the time it takes for the ESP chip to power on and execute the app_main function. The unoptimized startup process usually takes a long time (generally around 300 milliseconds), making it unable to meet the requirements of applications with high real-time requirements (such as turning on/off lights at any time). At the same time, it also accompanies high power consumption, resulting in high average power consumption in Deep-sleep low-power mode. To avoid these problems, fine optimization of the startup process is necessary.

Hardware and Software Environment

  • Hardware: ESP32-S3 and ESP32-C6

  • Software: ESP-IDF v5.2.1

Optional Optimization Items

Configure the following options via menuconfig to significantly reduce startup time:

  1. Disable Bootloader Log Printing

    • CONFIG_BOOTLOADER_LOG_LEVEL_NONE=y

    • CONFIG_BOOTLOADER_LOG_LEVEL=0

  2. Skip Image Validation

    • CONFIG_BOOTLOADER_SKIP_VALIDATE_IN_DEEP_SLEEP=y

    • CONFIG_BOOTLOADER_SKIP_VALIDATE_ON_POWER_ON=y

    • CONFIG_BOOTLOADER_SKIP_VALIDATE_ALWAYS=y

  3. Disable Boot ROM Log Printing

    • CONFIG_BOOT_ROM_LOG_ALWAYS_OFF=y

    In addition to this configuration, you also need to use the espefuse.py command in the terminal to configure the eFuse values related to controlling ROM log output (see the Boot Log Printing Control section of the Technical Reference Manual <https://www.espressif.com/sites/default/files/documentation/esp32-s3_technical_reference_manual_en.pdf>`__ for details; note that writing eFuse operations is irreversible). The specific command is as follows:

    espefuse.py burn_efuse UART_PRINT_CONTROL 3
espefuse.py burn_efuse DIS_USB_SERIAL_JTAG_ROM_PRINT 1

    After running the above two commands, you can use the espefuse.py summary command to check whether the writing is successful. If you see the following information, it means the configuration is successful:

    log_efuse

  4. Modify SPI Flash Mode and Frequency

    • CONFIG_ESPTOOLPY_FLASHMODE_QIO=y

    • CONFIG_ESPTOOLPY_FLASHFREQ_80M=y

  5. Disable Boot Calibration

    • CONFIG_ESP_PHY_CALIBRATION_AND_DATA_STORAGE=y

    • CONFIG_ESP_PHY_CALIBRATION_MODE=1

  6. Modify FreeRTOS Configuration

    • CONFIG_FREERTOS_UNICORE=y

    • CONFIG_FREERTOS_HZ=1000

  7. Disable Log Printing

    • CONFIG_LOG_DEFAULT_LEVEL_NONE=y

    • CONFIG_LOG_DEFAULT_LEVEL=0

If further optimization of the time to connect to the AP after power-on is required on the basis of optimizing the startup time, the following operations can be performed synchronously:

  1. Enable LWIP_DHCP_RESTORE_LAST_IP Configuration Option

    • CONFIG_LWIP_DHCP_RESTORE_LAST_IP=y

Startup Time and Startup Power Consumption Statistics

Startup time statistics of ESP32-S3 at different CPU frequencies:

CPU Frequency

80 M

160 M

240 M

Startup Time Before Optimization (ms)

318.8

318.7

318.7

Startup Power Consumption Before Optimization (mA)

44.1

51.4

57.3

Startup Time After Optimization (ms)

26.87

26.875

26.965

Startup Power Consumption After Optimization (mA)

29.69

29.77

29.74

Startup time statistics of ESP32-C6 at different CPU frequencies:

CPU Frequency

80 M

120 M

160 M

Startup Time Before Optimization (ms)

328.0

327.9

327.8

Startup Power Consumption Before Optimization (mA)

34.1

35.8

37.6

Startup Time After Optimization (ms)

33.31

33.315

33.315

Startup Power Consumption After Optimization (mA)

28.23

28.19

28.16

Note

Startup power consumption is the average current consumption during the entire startup process.